You spawn in a world that has only one biome, MushroomIsland.
The goal is to try and survive normally but without any mobs or animals in the world. There is a mod that blocks all entitys (apart from bosses and mooshrooms) from spawning, that means you are not able to get their drops.
In addition to that, this world has no caves, the only choice you have is to strip mine.
For finding trees I added a mod called scanter. When you use the keybind, this mod allows you to use your sniffing powers and find leaves.
Blue_future A.K.A CommandIL: